Expandable guide sheath and apparatus and methods for making them

ABSTRACT

Apparatus and methods are provided for providing access to a body lumen. The apparatus includes a tubular member including a proximal end, a distal end sized for insertion into a body lumen, and a lumen extending between the proximal and distal ends. A pushable stiffening member extends from the distal end of the tubular member, the elongate member terminating in a distal tip. An expandable sheath extends along at least a portion of the stiffening member, the sheath being expandable from a contracted condition to minimize a profile of the sheath to allow insertion along with the stiffening member into a body lumen, and an enlarged condition wherein the sheath at least partially defines a lumen communicating with the tubular member lumen. In one embodiment, the sheath includes an outer lumen and an inner lumen floating within the outer lumen, and the stiffening member is carried in the inner lumen.

This application claims benefit of provisional applications Ser. Nos.60/508,489, 60/508,490, and 60/508,491, all filed Oct. 2, 2003, and60/551,901, filed Mar. 9, 1004. The entire disclosures of theseapplications are expressly incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to apparatus and methods fordelivering instruments and/or agents during a medical procedure, and,more particularly, to guide sheaths for accessing body lumens and/ordelivering instruments into body lumens of a patient, and to methods formaking and using them.

BACKGROUND

Minimally invasive procedures have been implemented in a variety ofmedical settings, e.g., for vascular interventions, such as angioplasty,stenting, embolic protection, electrical heart stimulation, heartmapping and visualization, and the like. These procedures generally relyon accurately navigating and placing instruments within a patient'svasculature.

During such procedures, a target vessel may be accessed using aguidewire advanced through the intervening vasculature into the targetvessel, thereby providing a “railway” to the vessel. One or moreinstruments, e.g., catheters, sheaths, and the like, may be advancedover the guidewire or “rail” into the vessel. Thus, a diagnostic and/ortherapeutic procedure may be performed by advancing one or moreinstruments over this railway.

There are many risks involved with advancing instruments over aguidewire. For example, a catheter or other instrument may skive orotherwise damage a wall of a vessel, particularly as the instrumentpasses through narrow passages or tortuous anatomy involving sharpbends. Such instruments also risk dislodging embolic material or evenperforating the vessel wall.

In addition, it is often desirable to access very small vessels deepwithin the body, e.g., within a patient's heart, for example, to place aventricular pacing lead within a coronary vein. However, theinstrument(s), e.g., guide sheath, lead, etc., may have a relativelylarge cross-section and/or may have a relatively blunt distal tip,making it difficult to advance such instruments as deeply as desiredinto such small vessels.

Accordingly, apparatus and methods for delivering instruments into bloodvessels or other body lumens and/or for otherwise accessing vessels orother body lumens would be useful.

SUMMARY OF THE INVENTION

The present invention is directed generally to apparatus and methods forproviding access to body lumens and/or for delivering instruments and/oragents into body lumens during a medical procedure. More particularly,the present invention is directed to guide sheaths and methods formaking and using such sheaths to facilitate delivering instrumentsand/or agents into body lumens of a patient, e.g., within the patient'scoronary, neuro, and/or peripheral vasculature, within the patient'sgastrointestinal tract, urogenital tract, respiratory tract, lymphaticsystem, and/or within surgically created passages.

In accordance with one embodiment of the invention, an apparatus isprovided for accessing a body lumen that includes a tubular proximalportion, and an expandable distal portion. In one embodiment, theproximal portion may include a proximal end, a distal end sized forinsertion into a body lumen, and a lumen extending between the proximaland distal ends. The distal portion may include an elongate pushableand/or stiffening member extending from the distal end of the tubularmember, and an expandable sheath that is expandable from a contractedcondition to minimize a profile of the sheath to allow insertion alongwith the elongate member into a body lumen, and an enlarged conditionwherein the sheath at least partially defines a lumen communicating withthe tubular member lumen. through the sheath.

In accordance with another embodiment, a method is provided foraccessing a body lumen using an apparatus including a tubular proximalportion and an expandable distal portion having a size smaller than theproximal portion. The distal portion is advanced into a patient's body,e.g., vasculature, with an expandable sheath thereon in a contractedcondition. The proximal portion has sufficient length such that a distalend of the proximal portion may reach a first location within thepatient's body, e.g., including relatively large body lumens, passages,or chambers, such as the vena cava, right atrium, and/or coronary sinus.With the proximal portion reaching the first location, the distalportion may extend into relatively smaller body lumens, such as thecoronary veins, to a target location that is to be accessed. Theexpandable sheath may be expanded, thereby providing a substantiallycontinuous lumen through the proximal and distal portions to the targetlocation.

In one embodiment, a cardiac pacing lead may be advanced through theproximal portion and the expandable sheath to deliver the lead to thetarget location. Because such a lead may be floppy, the proximal portionmay guide the lead through the relatively large body lumens, passages,or chambers, while the expandable sheath may guide the lead throughrelatively small and/or tortuous body lumens to the target location.Once the lead is delivered to the target location, the apparatus may beremoved.

In accordance with yet another embodiment, an apparatus is provided foraccessing a body lumen that includes an expandable tubular memberincluding a proximal end, a distal end sized for insertion into a bodylumen, and a side wall. The side wall defines an outer lumen extendingbetween the proximal and distal ends and an inner lumen extendingbetween the proximal and distal ends, the inner lumen at least partiallyfloating within the outer lumen. An elongate stiffening member may bedisposed within the inner lumen and may extend between the proximal anddistal ends of the expandable tubular member. The elongate member may beattached to or free within the inner lumen.

In one embodiment, the side wall includes a sheet or film having firstand second side edges rolled into a tubular shape. The sheet may beattached to itself adjacent the side edges to define the outer lumen,such that the side edges extend into the outer lumen to at leastpartially define the inner lumen. For example, the first and second sideedges may be attached to one another to define the inner lumen.

In addition or alternatively, an inner surface of the outer lumen mayinclude lubricious material. Optionally, a third lumen may be providedwithin the outer lumen, for example, by attaching a sheet or film to theside wall.

In accordance with still another embodiment, a method is provided formaking an expandable sheath using a film having first and second ends,and first and second side edges. The film includes a first lubriciouslayer and a second layer. In an exemplary embodiment, the first layermay include PTFE or ePTFE, and the second layer may include FEP.

The film may be rolled such that the first and second side edges areadjacent one another to define a lumen such that the second layer isinside the lumen and the first layer is outside the lumen. The secondlayer may be bonded to itself at or near the first and second sideedges. The film may then be inverted such that the second layer isoutside the lumen and the first layer is inside the lumen, therebyproviding a tubular member having a lubricious material within thelumen.

In one embodiment, after the film is rolled, the second layer may bebonded to itself along a plurality of seams extending between the firstand second ends of the film to define first and second lumens adjacentone another. The film may be inverted through the first lumen such thatthe second lumen is located within the first lumen. Thus, the secondlumen may extend from a wall of the outer lumen, thereby coupling thesecond lumen at least partially to the first lumen, while allowing thesecond lumen to float within the first lumen.

Optionally, an elongate stiffening and/or pushable member may beattached to or otherwise received within the second lumen. Thus, theelongate member may at least partially float within the first lumen.

In accordance with yet another embodiment, a method for accessing a bodylumen of a patient using an apparatus that includes an expandable sheathincluding an outer lumen and an inner lumen at least partially floatingwithin the outer lumen, and an elongate stiffening and/or pushablemember within the inner lumen. The elongate member may be introducedinto a body lumen with the expandable sheath in a contracted condition,e.g., by pushing a proximal end of the elongate member.

Once a distal end of the sheath attains a target location, theexpandable sheath may be expanded to an enlarged condition such that theouter lumen extends through the body lumen to the target location. Oneor more instruments, e.g., a cardiac pacing lead, may be advancedthrough the outer lumen of the expandable sheath into the targetlocation. Because the inner lumen, and consequently, the elongatemember, are at least partially floating within the outer lumen, thestiffening member may move relative to the outer lumen as the expandablesheath extends through tortuous anatomy, thereby reducing the risk ofthe expandable sheath kinking or buckling. After the one or moreinstruments are delivered into the target location, the apparatus may beremoved.

In accordance with still another embodiment, a handle apparatus isprovided that includes an outer member including proximal and distalends, and a lumen extending therebetween, an elongate tubular memberextending from the distal end of the outer member, and an inner memberconnectable to the outer member. The handle apparatus may also include acutting element, e.g., detachably or permanently attached to the innermember. The inner member may include a lumen for receiving one or moreinstruments therethrough for delivering the instrument(s) into thetubular member extending from the outer member.

In one embodiment, the cutting element is coupled to the inner membersuch that, when the outer member is withdrawn proximally relative to theinner member, the cutting element may cut through the tubular member toallow the tubular member to be removed around the inner member. If aninstrument is disposed through the inner member, the instrument mayremain in place while the outer member and tubular member are removed.

In accordance with yet another embodiment, a method is provided fordelivering an instrument into a branch body lumen from a main body lumenwithin a patient's body. A distal portion of a sheath apparatus may beadvanced into the patient's body until a distal end of the sheathapparatus is disposed in the main body lumen adjacent the branch bodylumen. An occlusion member on the distal end of the sheath apparatus maybe expanded within the main body lumen. An instrument, e.g., a cardiaclead, may be introduced into the sheath apparatus, the instrumentpassing through an expandable sheath on the sheath apparatus until adistal end of the instrument is adjacent the occlusion member. Theinstrument may be advanced further, the occlusion member at leastpartially directing the distal end of the instrument into the branchbody lumen.

For example, in one embodiment, the occlusion member may be expandedwithin the main body lumen distal to the branch body lumen, and theinstrument may be advanced until the distal end of the instrument exitsan outlet of the expandable sheath and is exposed within the main bodylumen. The instrument may be advanced further such that the exposeddistal end contacts the occlusion member, the occlusion memberdeflecting the instrument into the branch body lumen. Alternatively, theocclusion member may include a passage therein communicating with theexpandable sheath, and the instrument may be advanced through thepassage until the instrument exits transversely from the occlusionmember into the branch body lumen.

In accordance with still another embodiment, a sleeve is provided thatmay be delivered within a coronary sinus of a patient's heart. In oneembodiment, the sleeve may include a tubular section and one or morestent-like structures, e.g., on one or both ends of the tubular section.The sleeve may be carried on a cardiac lead or other instrument beingdelivered through the coronary sinus or on a sheath or other deliveryapparatus used for delivering the instrument.

During use, the sleeve may be delivered within the coronary sinus, e.g.,while delivering the instrument through the coronary sinus. For example,the instrument may be a cardiac lead that is delivered into a coronaryvein accessed via the coronary sinus.

Other aspects and features of the present invention will become apparentfrom consideration of the following description taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a first embodiment of a sheathapparatus, including a tubular proximal portion and an expandable distalportion.

FIG. 1B is a perspective detail of an intermediate portion of theapparatus of FIG. 1.

FIG. 2 is a side view of an intermediate portion of the apparatus ofFIGS. 1A and 1B.

FIGS. 2A-2F are cross-sections of the apparatus of FIG. 2, taken alonglines 2A-2A to 2F-2F, respectively.

FIG. 3 is a side view of a distal end of the apparatus of FIG. 1.

FIG. 4 is a side view of an intermediate portion of an alternativeembodiment of a sheath apparatus.

FIG. 5 is a cross-section of the apparatus of FIG. 4, taken along line5-5.

FIG. 6 is a side view of another embodiment of a sheath apparatus,including a tubular proximal portion and an expandable distal portion.

FIGS. 6A-6C are cross-sections of the apparatus of FIG. 6, taken alonglines 6A-6A, 6B-6B, and 6C-6C, respectively.

FIG. 7 is a cross-section of a patient's body, showing a method foraccessing a vessel within the patient's heart using the apparatus ofFIG. 1.

FIGS. 8A-8J are cross-sections of a patient's body, showing a method fordelivering a cardiac lead into a coronary vein within a patient's heart.

FIG. 9A and 9B are side and perspective views, respectively, of a handleapparatus that may be provided on a proximal end of a sheath apparatus.

FIGS. 10A and 10B are perspective views of inner and outer members ofthe handle apparatus of FIG. 9, respectively.

FIG. 10C is a perspective view of the inner and outer members of FIGS.10A and 10B assembled together.

FIG. 11 is a side view of another embodiment of a handle apparatus,including a detachable slitter.

FIG. 12 is a side view of yet another embodiment of a handle apparatus,including a separate slitter.

FIGS. 13A and 13B are side and perspective views, respectively, of stillanother embodiment of a handle apparatus including a pivotable slitterattached thereto.

FIGS. 14A and 14B are side and perspective views, respectively, ofanother embodiment of a handle apparatus with an integral slitter.

FIGS. 15A-15C are perspective views of yet another embodiment of ahandle apparatus, including an outer member and an inner member slidablerelative to one another.

FIGS. 16A-16C are perspective views of alternative embodiments of aproximal end of a handle apparatus for a sheath apparatus.

FIG. 17 is a perspective view of a protective sleeve that may be carriedby a cardiac lead.

FIGS. 18A-18C are cross-sectional views of a patient's body, showing amethod for delivering and removing a removable cardiac lead into thepatient's heart that includes the protective sleeve of FIG. 17.

FIGS. 19A-19C are cross-sectional views of a patient's body, showing amethod for delivering a lead into a branch vessel from a main vessel.

FIG. 20 is a side view of the apparatus of FIGS. 1A and 1B, having anobturator inserted therein for providing a transition between theproximal and distal portions of the apparatus.

FIGS. 21A, 22A, and 23A are exploded side views of distal tips of astiffening member having multiple sections providing a variablestiffness for the distal tip.

FIGS. 21B, 22B, and 23B are side views of the distal tips of FIGS. 21A,22A, and 23A, respectively, with the sections assembled together.

FIGS. 24A and 24B are side views of another embodiment of a sheathapparatus including a stiffening member and an expandable sheath carriedby the stiffening member in collapsed and expanded conditions,respectively.

FIGS. 25-29 are cross-sectional views of alternative embodiments of thesheath apparatus of FIGS. 24A and 24B.

FIGS. 30A and 30B are cross-sectional views of additional alternativeconfigurations of the sheath apparatus of FIGS. 24A and 24B.

FIGS. 31A-31C are cross-sectional views showing a method forconstructing a flexible sheath.

FIG. 32 is a cross-sectional side view of yet another embodiment of aflexible sheath providing an automatically sealing lumen.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning to the drawings, FIGS. 1A and 1B show a first embodiment of anapparatus 8 for providing access within a body lumen (not shown) and/orfor delivering one or more instruments (also not shown) within a bodylumen, such as a vessel within a patient's vasculature, a passage withina patient's gastrointestinal tract, urogenital tract, respiratory tract,lymphatic system, and the like.

Generally, the apparatus 8 includes a tubular proximal portion 10 and anexpandable distal portion 18. The tubular proximal portion 10 is anelongate tubular member, e.g., a catheter, sheath, and the like,including a proximal end 12, a distal end 14 sized for insertion into abody lumen, and a lumen 16 extending between the proximal and distalends 12, 14. Optionally, the tubular proximal portion 10 may include oneor more additional lumens (not shown), e.g., for receiving a guide wire,inflation media, and/or for perfusion, as described further below. Suchadditional lumens may be disposed concentrically around one another orin a side-by-side arrangement.

The wall of the tubular portion 10 may be sufficiently thick such thatthe diameter (or other peripheral dimension) of the tubular portion 10remains substantially fixed during use of the apparatus 8. The wall ofthe tubular portion 10 may be rigid or flexible, althoughself-supporting such that the tubular portion 10 does not collapse onitself. The tubular portion 10 may be sufficiently flexible to allow thetubular portion 10 to bend or otherwise be advanced through a patient'svasculature, while minimizing the risk of kinking or buckling.

The tubular portion 10 may be formed from uniform or variableflexibility material along its length between the proximal and distalends 12, 14, as desired. For example, it may be desirable for theproximal end 12 to be substantially rigid or semi-rigid, e.g., tofacilitate pushing the apparatus 8, while the distal end 14 may besemi-rigid or substantially flexible to accommodate advancement throughbends within a patient's vasculature.

The tubular portion 10 may be formed from a variety of materials, suchas PTFE, FEP, PFA, PE, Polyamides (Nylon), Polyimide, Pebax, Urethane,and the like. Optionally, the tubular portion 10 may include one or morebraids or coils, e.g., embedded within the wall, to providereinforcement for the tubular portion. In exemplary embodiments, thetubular portion 10 may have a diameter between about half and fivemillimeters (0.5-5 mm), a wall thickness between about 0.02 and onemillimeters (0.02-1.0 mm) (cross-sectional configurations, i.e.multi-lumen cross-sections, and the like may cause wall thicknesses tovary), and a length between about ten and one hundred ten centimeters(10-110 cm). For example, if a subclavian approach is to be used, theproximal portion 10 may have a length of about thirty centimeters (30cm) or less, while if a femoral approach is to be used, the proximalportion 10 may have a length of about one hundred ten centimeters (110cm) or more. In one embodiment, the tubular portion 10 may have a lengthsufficient to reach the vena cava, the right atrium, or the coronarysinus of a patient's heart from a percutaneous entry location, such as asubclavian vein, as described further below.

With continued reference to FIGS. 1A and 1B, the expandable distalportion 18 generally includes an elongate stiffening member 20 providinga “backbone” for the distal portion 18 and an expandable sheath 30. Thestiffening member 18 and/or expandable sheath 30 may be attached to orotherwise extend distally from the distal end 14 of the tubular portion10, as described further below. The stiffening member 20 facilitatesadvancing the expandable sheath 30 through one or more body lumens,e.g., through a patient's vasculature. The distal portion 18 may besimilar in construction and use as the apparatus disclosed inapplication Ser. No. 10/423,321, filed Apr. 24, 2003, the entiredisclosure of which is expressly incorporated by reference herein. Inaddition or alternatively, the distal portion 18 may be constructedusing materials and/or methods similar to any of the embodimentsdescribed elsewhere herein.

The stiffening member 20 may be a solid or hollow guidewire, catheter,thread or other filament (e.g., a monofilament), and/or other solid orhollow elongate member. The stiffening member 20 may be sufficientlyflexible to facilitate advancement through tortuous anatomy withoutcausing dissection or perforation, yet may have sufficient columnstrength and/or torque-ability to be “pushable,” i.e., such that thestiffening member 20 may be advanced through a body lumen by pushing theproximal end 12 of the tubular portion 10 without substantial risk ofkinking and/or buckling. In addition, the stiffening member 20 may alsoprovide sufficient support to facilitate introducing secondary devices,such as a cardiac lead, through the distal portion 18. Cardiac leads orother floppy devices may be difficult to deliver, because of theirability to “prolapse” or double over on themselves in large lumens, likeatria, rather than advance to a desired proper location.

In addition, the stiffening member 20 may have sufficient length to beadvanced from a first location where the proximal portion 12 terminates,e.g., within the right atrium or coronary sinus of a heart, and a siteto be accessed and/or treated, e.g., a coronary vein, as describedfurther below. In exemplary embodiments where the stiffening member 20is attached to the distal end 14 of the proximal portion 10, thestiffening member 20 may be between about ten and fifty centimeters(10-50 cm), or may be not more than about thirty centimeters (30 cm).Alternatively, the stiffening member 20 may extend proximally the entirelength of the proximal portion 10, e.g., within or along the proximalportion 10, and therefore may have additional length corresponding tothe length of the proximal portion 10.

As shown in FIGS. 1A-3, the stiffening member 20 may be an elongatemember including a proximal end 22, and a distal end 24 having a sizeand/or shape for insertion into a body lumen. Optionally, the stiffeningmember 20 may terminate in a rounded or other substantially atraumaticdistal tip 28, e.g., a “J” tip, a balloon or other expandable member,and the like, as explained further below. If desired, the distal tip 28may be shaped to provide steerability and/or directionality, or mayinclude one or more internal elements to provide a steerable distal tip.

Optionally, as shown in FIGS. 21-23, the distal tip 28 may be formedfrom multiple sections of tubing or other material having differentstiffness or modulus of elasticity. For example, as shown in FIGS. 21Aand 21B, the distal tip 28 a may include a first tubular section 28 a 1having a stiffness similar to the adjacent portion of the stiffeningmember (not shown). Distally adjacent tubular sections 28 a 2-28 a 4 mayhave progressively less stiffness, e.g., such that the distal-mostsection 28 a 4 is “floppy” or soft, which may facilitate advancing thedistal tip 28 a through tortuous anatomy.

Alternatively, as shown in FIGS. 22A and 22B, sections 28 b 1-28 b 3 ofthe distal tip 28 b may be angled on the ends to be attached to oneanother. This may create a distal tip 28 b whose stiffness changes lessabruptly. In a further alternative, shown in FIGS. 23A and 23B, thesections 28 c 1-28 c 4 may be beveled or otherwise staggered to providea more gradual and/or continuous change in stiffness along the distaltip 28 c.

Optionally, the stiffening member 20 may include one or more lumens 26extending between the proximal and distal ends 22, 24. For example, inthe embodiment of FIGS. 1A and 2, the stiffening member 20 includes asingle lumen 26, best seen in FIG. 2F. Alternatively, in the embodimentof FIG. 6, the stiffening member 20′ includes two side-by-side lumens 26a,′ 26 b,′ best seen in FIGS. 6B and 6C. The lumen(s) may be sized toallow fluids to be delivered therethrough and/or to receive a guidewire, catheter, or other instrument (not shown) therethrough.

As shown in FIG. 2F, the stiffening member 20 may have a cylindrical orother substantially symmetrical cross-section, e.g., including a singlelumen 26. Alternatively, as shown in FIGS. 6B and 6C, the stiffeningmember 20′ may have an asymmetrical cross-section, e.g., including aplurality of lumens 26 a,′ 26 b.′ In other embodiments, the stiffeningmember may have an arcuate cross-section (not shown), such as thosedisclosed in application Ser. No. 10/432,321, incorporated by referenceabove. The diameter or other cross-section of the stiffening member 20is substantially smaller than that of the tubular proximal portion 10,e.g., between about 0.05-5 millimeters, or between about 0.2-2millimeters.

Optionally, as best seen in FIG. 3, the stiffening member 20 may includea balloon or other expandable occlusion member 27 on the distal end 24.If a balloon 27 is provided, the stiffening member 20 may include aninflation lumen (not shown) that extends through the stiffening member20 from the proximal end 12 (see FIG. 1A) to communicate with aninterior of the balloon 27. A source of inflation media, e.g., a syringeof saline (not shown) may be coupled to port 56 (see FIG. 1A) that maycommunicate with the inflation lumen. Exemplary occlusion members thatmay be provided and methods for using them are disclosed in co-pendingapplication Ser. No. 10/934,082, filed Sep. 2, 2004, the entiredisclosure of which is expressly incorporated by reference herein.

In addition or alternatively, the stiffening member 20 may include oneor more outlet ports 29 on the distal end 24, e.g., distal to theballoon 27, as shown in FIG. 3, or proximal to the balloon 27 (notshown). As shown in FIGS. 6-6C, if the stiffening member 20′ includes aballoon 27′ and one or more outlet ports 29,′ the stiffening member 20′may include two lumens 26 a,′ 26 b′ communicating with the interior ofthe balloon 27′ and the outlet ports, respectively.

The stiffening member 20 may be formed from a variety of materials andusing various methods. For example, the stiffening member 20 may beformed from plastic, glass, metal, or composites of such materials usingknown methods, such as extrusion and the like, thereby providing adesired combination of flexibility and column strength. In exemplaryembodiments, the stiffening member 20 may be formed from one or more ofpolyimide, polyamide (nylon)), Ultem, PEEK, Nitinol, and optionally, mayinclude braid and/or coil reinforcing polymers, similar to othercomponents described herein.

Turning to FIGS. 1B and 2, a transition may be provided between thedistal end 14 of the tubular portion 10 and the proximal end 22 of thestiffening member 20. As shown, the distal end 14 of the tubular portion10 may be beveled or otherwise tapered, e.g., by molding-in the taperedshape or by cutting or otherwise removing a section of the distal end14. Such a shape may facilitate advancing the tubular portion 10 into abody lumen within which the smaller stiffening member 20 has beenpreviously introduced, as described further below.

In addition or alternatively, as shown in FIG. 20, an obturator 40 maybe provided that includes a proximal end 42, and a tapered and/orrounded distal end 44 sized to be slidably inserted into the lumen 26 ofthe tubular portion 10. The obturator 40 may have a length correspondingto a length of the tubular portion 10 such that the distal end 44 of theobturator 40 extends partially into the expandable distal portion 18when the obturator 40 is fully advanced into the tubular portion 10. Thedistal end 44 of the obturator 40 may be relatively flexible and/or softto provide an atraumatic transition between the tubular proximal portion10 and the expandable distal portion 18.

Returning to FIGS. 1B and 2, the proximal end 22 of the stiffeningmember 20 may be attached to the distal end 14 of the tubular portion10, e.g., such that the stiffening member extends axially and/ortangentially from the wall of the tubular portion 10. The stiffeningmember 20 may be attached to the tubular portion 10, e.g., by one ormore of chemical bonding, thermal bonding, sonic welding, interferencefit, and/or one or more cooperating connectors. Alternatively, thetubular portion 10 and stiffening member 20 may be formed as a singlepiece, e.g., by extrusion, injection molding, and the like.

With additional reference to FIGS. 1A-3, the expandable sheath 30generally includes a proximal end 32, a distal end 34, and one or moreside walls extending between the proximal and distal ends 32, 34,thereby at least partially defining a lumen 36. As used herein, the term“sheath” may include any structure that at least partially defines alumen, whether the structure is substantially tubular or only partiallydefines the lumen 36.

The sheath 30 may be expandable from a contracted condition (not shown)to an enlarged condition, as shown in FIG. 1A. When the sheath 30 is inthe contracted condition, the distal portion 18 may assume a low profileto facilitate insertion into a body lumen (not shown). To place thesheath 30 in the contracted condition, the sheath 30 may be folded,twisted, wrapped, or otherwise compressed around or adjacent to thestiffening member 20 (e.g., using an internal vacuum with the lumen 36of the sheath 30 and/or an external force). In another embodiment, thesheath 30 may be left unconstrained. The “limpness” of the sheath 30 mayallow the sheath material to readily deflect when the sheath 30 contactsany bodily structures, such that the sheath 30 may perform as if it weremaintained in a collapsed configuration, when it is not actuallyconstrained.

Optionally, the sheath 30 may be secured in the contracted condition,e.g., using a constraint (not shown), such as a sheath, tether, orreleasable adhesive or bonding material at one or more locations orcontinuously along the sheath 30. Alternatively, the sheath 30 maysimply maintain the contracted condition until an external force, e.g.,fluid or an instrument, are delivered therein to expand the sheath 30towards the enlarged condition. Exemplary apparatus and methods forplacing and/or maintaining the sheath 30 in the contracted condition aredisclosed in application Ser. No. 10/423,321, incorporated by referenceabove. In the enlarged condition, the sheath 30 may unfold, untwist,unwrap, or otherwise expand to at least partially define the lumen 36,e.g., for receiving a fluid (e.g., a medicament, anti-thrombotic agent,and the like) and/or one or more instruments therethrough (not shown).

Because the sheath 30 is relatively thin-walled, the distal portion 18may attain a relatively low profile when the sheath 30 is in thecontracted condition compared to the proximal portion 10. For example,with the sheath 30 in the contracted condition, the distal portion 18may have a maximum diameter between about 0.1 and about ten millimeters(0.1-10 mm), or between about 0.2 and about three millimeters (0.2-3mm). Conversely, a relatively large lumen 36 may be provided when thesheath 30 is expanded to the enlarged condition, e.g., having a diameteror other maximum cross-section between about 0.3 and about one hundredmillimeters (0.3-100 mm), or preferably between about 0.3 and abouttwenty millimeters (0.3-20 mm).

The sheath 30 may be formed from relatively thin, flexible material, ascompared to the stiffening member 20 and/or tubular proximal portion 10.Thus, the sheath 30 may be “flimsy,” i.e., may have little or norigidity such that the sheath 30 provides little resistance to expansionand/or contraction, and/or may conform substantially to anatomy withinwhich it is deployed. As used herein, “flimsy” means that the materialof the sheath 30 is not biased to assume any particular configuration orshape, and therefore, the sheath 30 may adopt whatever shape and/orconfiguration that is imposed upon it, e.g., by being folded orotherwise compressed, by being subjected to external or internalpressure or force, and the like. To achieve this, the sheath 30 may havea relatively thin wall thickness, e.g., between about 0.001-1.25millimeters, or between about 0.005-0.06 millimeter.

The sheath 30 may be constructed of one or more materials that may befabricated to a relatively thin, flexible configuration, e.g.,polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene(ePTFE), fluorinated ethylenepropylene (FEP), polyethyleneteraphathalate (PET), urethane, olefins, polyethylene (PE), silicone,latex, isoprene, chronoprene; and the like. The sheath 30 may be formedfrom lubricious material and/or may be coated, e.g., with silicone orother coating, e.g., for facilitating inserting one or more instruments(not shown) through the lumen 36.

In some embodiments, it may be desirable that the internal surface ofthe sheath 30 be lubricious to allow for smooth passage of aninstrument, such as an electrical pacing lead (not shown), therethrough.This may be accomplished by forming the sheath 30 out of a lubriciousmaterial such as, a hydrophobic fluoropolymer. Alternatively, the sheath30 may be formed from material that has been surface-treated and/orcoated with a hydrophilic coating material. If it is particularlydifficult to treat or coat the interior surface of the sheath 30, thetreatment or coating material may be applied to the exterior surface ofthe sheath 30. The sheath 30 may then be inverted or “everted,” forexample, by pulling one end of the sheath 30 through the sheath lumen toplace the exterior treated/coated surface on the interior of the sheath30 (i.e., turn the sheath 30 inside-out).

The sheath 30 may be formed from thin-walled polymeric tubing or a thinpolymeric film. With respect to tube-based structures, the tubing may beextruded (or co-extruded if multiple lumens are used as is described inmore detail below) to a thin wall. Alternatively, one or morepost-processing steps, such as blow molding, stretching, or drawing tubethrough a heated die may be used to form the thin walled sheath 30. Instill another embodiment, a thin film may be produced and rolled into atubular configuration. In this embodiment, the thin film may besurface-treated and/or coated before being rolled into the tubularconfiguration.

With respect to thin film-based structures, a seam may be formed alongall or a portion of the length of the sheath 30. The seam may be formedfrom any number of methods, for example, chemical bonding withadhesives, heat sealing, ultrasonic welding, laser welding, ormechanical bonding using stitching or the like.

As described above, in one embodiment, the sheath 30 may be formed froma lubricious fluoropolymer. For example, a thin-walled sheath 30 may beformed by rolling a cast thin film formed from PTFE having a layer ofFEP formed thereon into a tubular structure. The FEP may then be sealed(for example, by heat sealing) to form the final tubular structure. ThePTFE layer is preferably disposed on the interior surface of the sheath30 since PTFE is more lubricious than FEP.

In still another alternative embodiment, the sheath 30 may be formedfrom ePTFE manufactured into a thin-walled tube (or multiple tubes) orthin film. Additional lumens may also be formed within the sheath 30.For example, these additional lumens may be used to house the backbone(i.e., elongate stiffening member 20) or used to inject contrast forimaging and/or perfusing blood or other fluids. As one example,additional lumens may be formed by joining un-sintered PTFE or ePTFEtube structures, which may then be heat-sealed along their lengths,followed by a sintering process.

In one embodiment, the sheath 30 is formed from substantially inelasticmaterial, i.e., such that a primary contribution to the sheath 30expanding and contracting is unfolding or folding the material of thesheath 30. Alternatively, the sheath 30 may be formed from an elasticmaterial such that a secondary contribution to the sheath 30 expandingand contracting is an elasticity of the material of the sheath 30, i.e.,such that a circumference or other peripheral dimension of the sheath 30may increase as the sheath 30 expands towards the enlarged condition.

The sheath 30 may be substantially nonporous. Alternatively, the sheath30 may be porous, for example, substantially continuously along itslength or at one or more locations, e.g., to allow fluid delivered intothe lumen 36 to pass through the wall of the sheath 30 in a desiredmanner, e.g., to deliver fluid to a wall of a vessel (not shown) throughwhich the sheath 30 extends. In a further alternative, the sheath 30 mayinclude one or more discrete openings (not shown) at one or morelocations along its length.

In addition or alternatively, the sheath 30 may include a thin mesh,e.g. a perforated urethane film and the like. In a further alternative,the lubricity of the sheath 30 may be enhanced by providing a lubriciouscoating, lining, ribbing, and the like (not shown), and/or applying alubricant, e.g., to the interior surface and/or outer surface of thesheath 30. The sheath 30 may include a single layer or multiple layersof such materials, such that a desired flexibility and lubricity isachieved. Thus, the sheath 30 may easily expand and/or line a body lumento reduce friction and/or accommodate instruments being advanced throughthe body lumen, as explained further below.

Optionally, the sheath 30 may include one or more reinforcing elements(not shown). For example, a wire, thread, filament, and the like, formedfrom plastic, glass, metal, or composites of such materials, may beattached to an outer surface, an inner surface, and/or embedded in awall of the sheath 30. In addition or alternatively, the sheath 30 mayinclude relatively thickened regions that may be formed directly fromthe wall material. The reinforcing element(s) may extendcircumferentially and/or helically around the sheath 30, and/or mayextend axially along the sheath 30, depending upon the reinforcementdesired. The reinforcement element(s) may also bias the sheath 30 toassume a desired shape or configuration when expanded towards theenlarged condition.

With particular reference to FIGS. 1B and 2, the proximal end 32 of thesheath 30 may be attached to the distal end 14 of the tubular portion10, e.g., by chemical bonding, thermal bonding, sonic welding,interference fit, and the like. Thus, as shown in FIG. 2B, the sheath 30may surround and overly the distal end 14 of the tubular portion 10 suchthat the lumen 16 of the tubular portion 10 communicates with the lumen36 of the sheath 30. When the sheath 30 is compressed to the contractedcondition, the proximal end 32 of the sheath 30 may be compressedagainst the tapered distal end 14 of the tubular portion 10.

Turning to FIGS. 4 and 5, an alternative embodiment is shown of anapparatus 8″ that includes an expandable distal portion 18″ extendingdistally from a tubular proximal portion 10.″ As shown, the tubularportion 10″ may include a proximal end (not shown), a distal end 14,″and one or more lumens extending therebetween. As shown, the tubularportion 10″ includes a single lumen 16″ and a pair of grooves 17″extending along the outer wall of the tubular portion 10.″Alternatively, the grooves 17″ may be replaced with one or moreadditional lumens (not shown), extending along the wall of the tubularportion 10.″ Unlike the previous embodiment, the distal end 14″ may besubstantially blunt, although alternatively, the distal end 14″ may alsobe beveled or otherwise tapered, similar to the previous embodiments.

The expandable distal portion 18″ may include a stiffening member 20″and an expandable sheath 30,″ similar to the previous embodiments. Thestiffening member 20″ may include a proximal end 22″ attached to thedistal end 14″ of the tubular portion 18,″ e.g., aligned with one of thegrooves 17″ such that a lumen 26″ within the stiffening member 20″communicates with the groove 17.″ A catheter, other tubular body, orcover (not shown) may be snapped into the groove 17″ or otherwiseattached to the tubular portion 10″ to provide a lumen communicatingwith the stiffening member 20.″

The tubular body or cover may extend at least partially towards theproximal end of the tubular portion 10,″ e.g., to provide a lumen forreceiving a guidewire or other element therethrough. For example, thetubular body may extend entirely to the proximal end of the tubularportion 10″ or to an intermediate location, e.g., to provide a rapidexchange lumen.

In addition, as best seen in FIG. 5, the sheath 30″ may include asupplemental lumen 37″ attached to or otherwise extending along a wallof the sheath 30,″ e.g., to provide a fluid-tight lumen for deliveringcontrast media or other fluids beyond the distal end of the sheath 30.″The lumen 37″ may be aligned with groove 17,″ which may include atubular body or cover, similar to the other groove 17.″

Returning to FIG. 1A, optionally, a proximal end 12 of the tubularproximal portion 10 may include a handle or other structure 50, e.g.,that may facilitate manipulating the apparatus 80 and/or inserting oneor more instruments into the lumen 16 of the tubular portion 10. Inaddition or alternatively, the handle 50 may include one or more valves,e.g., a hemostatic valve 52, that may substantially seal the lumen 16from proximal flow of fluid, yet accommodate instruments beingintroduced into the lumen 16. In addition, the handle 50 may include oneor more additional ports 54, 56 for communicating with the lumen(s)within stiffening member 20 and/or sheath 30.

Turning to FIGS. 9A-10C, an exemplary embodiment of a handle 50 is shownthat includes two portions 60, 70 including wings 58 that may facilitatemanipulation and/or stabilization of the handle 50. As shown, the handle50 includes an inner member 60 and an outer member 70 that areconnectable to and/or releasable from one another.

With particular reference to FIG. 10B, the inner member 60 may include arelatively short tubular section, e.g., between two and ten centimeters(2-10 cm) in length, and including a proximal end 62, a tapered distalend 64, and a lumen 66 extending therebetween. The proximal end 62 mayinclude one or more valves, e.g., hemostatic valve 52, that maysubstantially seal the lumen 66, yet accommodate insertion of one ormore instruments (not shown) therein. The inner member 60 may include aside port 54, e.g., including a hemostatic valve, a luer lock or otherconnector, and the like (not shown), that communicates with the lumen66. A source of fluid, e.g., a syringe of saline (not shown) may beconnected to the side port 54 for flushing or otherwise delivering fluidinto the lumen 66 (and consequently into the lumen of the sheath 30 orother apparatus coupled to the handle 50).

Optionally, the inner member 60 may include a blade 68 adjacent thetubular section, e.g., partially embedded or otherwise attached to theouter surface of the tubular section. The blade 68 may provide a slitterfor splitting or otherwise cutting the outer member 70, and/or one ormore portions of the sheath 30 (or other apparatus coupled to the handle50), as described further below.

Turning to FIG. 10A, the outer member 70 may include a tubular sectionincluding a proximal end 72, a distal end 74, and a lumen 76 extendingtherebetween. The outer member 70 may have a size such that the innermember 60 may be at least partially received within the lumen 76.Optionally, the outer member 70 may include a slot 78 extending distallyfrom the proximal end 72 that may receive the wing 58 of the innermember 60 to interlock the inner and outer members 60, 70. In addition,the slot 78 may align the blade 68 with a weakened or otherwise easilycut region 79 of the outer member 70. Alternatively, similar to theembodiment shown in FIG. 15A, the outer member 70 e may have a “C”shaped cross-section, including a continuous slot 78 e extending betweenthe proximal and distal ends 72 e, 74 e.

Returning to FIG. 10A, a stiffening member 20 may be attached to orotherwise extend distally from the outer member 70. The stiffeningmember 20 may be substantially permanently attached to the outer member70, e.g., extending along an exterior surface of the outer member 70, asshown. Alternatively, the stiffening member 20 may be detachable fromthe outer member 70. The outer member 70 may include a side port 56 thatcommunicates with a lumen (not shown) of the stiffening member 20. Theside port 56 may include a seal and/or connector, similar to the sideport 54. Alternatively, the stiffening member 20 may be connected to thedistal end 74 of the outer member 70, similar to the attachments betweenthe stiffening member 20 and proximal tubular portion 10 described above(e.g., as shown in FIGS. 2 and 4).

An expandable sheath 30 (not shown in FIG. 10A, see FIG. 9A) may beattached to or extend along the stiffening member 20. A proximal end 32of the expandable sheath 30 may surround or otherwise be attached to thedistal end 74 of the outer member 70 (e.g., similar to FIGS. 1B or 4).The stiffening member 20 and expandable sheath 30 may be constructedsimilar to any of the other embodiments described herein. Alternatively,a proximal tubular portion (not shown) may be attached to or otherwiseextend from the outer member 70, e.g., similar to the tubular portionsdescribed above, and an expandable distal portion (also not shown) mayextend from the tubular portion.

As shown in FIG. 10C, the distal end 64 of the inner member 60 may beinserted into the lumen 76 from the proximal end 72 of the outer membersuch that the wing 58 and blade 68 are received within the slot 78 inthe outer member 70, thereby assembling the handle 50. As assembled, thedistal end 64 of the inner member 60 may extend a short distance beyondthe distal end 74 of the outer member 70, e.g., adjacent the stiffeningmember 20 and/or partially into the expandable sheath 30. Receiving thewing 58 of the inner member 60 in slot 78 may limit relative movement ofthe inner and outer members 60, 70, e.g., while the handle 50 is beingmanipulated, separated, and/or while instruments (not shown) areinserted or removed from the inner member 60.

As described further below, when it is desired to remove the stiffeningmember 20 and expandable sheath 30, the outer member 70 may be withdrawnproximally relative to the inner member 60. This causes the blade 68 tocontact the weakened or easily cut region 79 of the outer member 70,e.g., to cut through the outer member 70. As the outer member 70 iswithdrawn further, the blade 68 may cut through the expandable sheath 30(and/or the tubular proximal portion, if present), causing theexpandable sheath 30 to split. Thus, the handle 50 may allow theexpandable sheath 30 to be removed, while leaving the inner member 60 inplace, e.g. with an instrument (not shown) maintained within the lumen66 of the inner member 60 substantially stationary.

In alternative embodiments, other handles may be provided on the sheathapparatus 8 or any other sheath apparatus described elsewhere herein. Inaddition, the handle apparatus described herein may be useful for otherapplications, including introducer sheaths (not shown) forcatheter-based procedures, and the like.

Turning to FIG. 11, a handle 50 a is shown that includes a relativelyshort tubular section 60 a, including a proximal end 62 a, a distal end64 a, and a lumen 66 a extending therebetween. The handle 50 a may be asingle piece tubular section, or may include multiple sections similarto the previous embodiment. A hemostatic valve 52 a may be provided inthe proximal end 62 a, similar to the previous embodiment, to seal thelumen 66 a while accommodating insertion of one or more instrumentstherein, e.g., guidewire 88. A stiffening member 20 and expandablesheath 30 may extend from the distal end 64 a of the tubular section 60a, similar to the previous embodiment. In addition, the handle 50 a mayinclude a first side port 54 a communicating with the lumen of thetubular section 60 a (and consequently, the lumen of the expandablesheath 30), and a second side port 56 a communicating with a lumen ofthe stiffening member 20.

Unlike the previous embodiment, the handle 50 a includes a detachableslitter tool 68 a that may be attached to the handle 50 a, e.g., alongthe tubular section 60 a. The slitter tool 68 a may be attached by oneor more tabs or other elements that may be broken, e.g., by bending theslitter 68 a relative to the tubular section 60 a. Once separated, theslitter 68 a may be used to split or otherwise cut the tubular section60 a and/or the expandable sheath 30 similar to other embodimentsdescribed herein.

Turning to FIG. 12, another embodiment of a handle 50 b is shown thatincludes a separate slitter tool 68 b, i.e., that is not attached to thehandle 50 b. Otherwise, the handle 50 b may include a tubular section 60b, stiffening member 20, expandable sheath 30, and side ports 54 b, 56b, similar to the previous embodiments.

Turning to FIGS. 13A and 13B, yet another embodiment of a handle 50 c isshown that includes a tubular section 60 c, stiffening member 20,expandable sheath 30, and side ports 54 c, 56 c, similar to the previousembodiments. A slitter tool 68 c is attached to the tubular section 60 cadjacent the seal 52 c. The slitter tool 68 c may be pivotally coupledto the tubular member 60 c such that the slitter tool 68 c may bepivoted to align a blade 69 c of the slitter tool 68 c with the tubularsection 60 c. Optionally, the tubular section 60 c may include inner andouter portions (not shown), similar to the other embodiments describedherein, such that the expandable sheath 30 may be split when the outerportion is withdrawn relative to the inner portion.

Turning to FIGS. 14A and 14B, still another embodiment of a handle 50 dis shown that includes a separate slitter tool 68 d that may be manuallyinserted into a proximal end 60 d of the tubular section 60 d to splitthe tubular section 60 d and the expandable sheath 30 attached thereto.The slitter tool 68 d may be insertable into the seal 52 d or may have asharpened tip that may penetrate through the seal 52 d to allow thetubular section 60 d and sheath 30 to be split.

FIGS. 15A-15C show another embodiment of a handle 50 e that includes aninner member 60 e and an outer member 70 e. Similar to the previousembodiments, the inner member 60 e may be slidably inserted into theouter member 70 e such that a wing 58 e of the inner member 60 e isreceived in slot 78 e in the outer member 70 e. A stiffening member 20and expandable sheath 30 may extend from the outer member 70 e, similarto the previous embodiments. Unlike the previous embodiments, thehemostatic seal 52 e may be removed from the inner member 60 e.

FIGS. 16A-16C show alternative embodiments of a handle including atoughy borst valve 52 f (FIG. 16A), a flip hemostatic valve 52 g (FIG.16B), and a completely removable hemostatic valve 52 h (FIG. 16C). Suchhandles may allow the valve to be removed to facilitate using a slittertool (not shown) to split the handle and/or sheath 30 extendingtherefrom.

During use, a sheath apparatus, such as apparatus 8 shown in FIG. 1A anddescribed above (or other apparatus described herein), may be used toprovide access to a vessel within a patient's body, e.g., a coronaryvein. It will be appreciated that the sheath apparatus described hereinmay also be used to provide access to a variety of body lumens, e.g., toperform a diagnostic and/or therapeutic procedure, such as the thosedisclosed in application Ser. No. 10/423,321, incorporated by referenceabove.

Generally (with reference to FIG. 1A for illustration only), theapparatus 8, with the expandable sheath 30 in a contracted condition,may be introduced into an entry site, e.g., a natural or created openingin a patient's body, and advanced into one or more body passages,including natural or created passages within the patient's body. Theapparatus 8 may be advanced from the entry site until a distal end 14 ofthe tubular proximal portion 10 is disposed at a first location, whilethe expandable distal portion 18 extends further to a second location.Because of its low profile, the expandable distal portion 18 may beeasily advanced through tortuous anatomy until the distal tip 28 isdisposed within relatively small, difficult to access body lumens. Thetubular proximal portion 10 may provide enhanced support, e.g., toaccommodate pushing one or more instruments (not shown) through theapparatus 8.

The sheath 30 may then be expanded to an enlarged condition, therebydefining a lumen 36 within the sheath 30. Thus, the apparatus 8 mayprovide a substantially continuous lumen, i.e., through the lumen 16 ofthe tubular proximal portion 10 and the lumen 36 of the sheath 30. Theresulting lumen may extend continuously from the entry site through anyintervening body passages to the target body lumen or site to provide apath from the entry site to the target body lumen or site.

A diagnostic and/or therapeutic procedure, such as the exemplaryprocedures described elsewhere herein, may be performed within the bodylumen via the lumen defined by the apparatus 8. For example, one or moreguidewires, catheters, leads, and the like may be advanced through thelumen provided by the apparatus 8. Upon completing the procedure(s), theapparatus 8 may be withdrawn from the body lumen, and entirely from thepatient's body.

Turning to FIGS. 7, an exemplary method is shown that uses a sheathapparatus 8 (or any of the sheath apparatus described herein) forproviding access to a target vessel within a patient's vasculature.Specifically, the apparatus 8 may be used to deliver an electricalcardiac lead (not shown), e.g., for a pacemaker, into a coronary vein96, e.g., adjacent to the left ventricle of the heart. Initially, theapparatus 8 may be advanced into the coronary vein 96 with an expandablesheath 30 carried by a stiffening member 20 in its contracted condition(not shown).

For example, with the sheath 30 collapsed, the apparatus 8 may beintroduced from a percutaneous entry site, e.g., a femoral vein orsubclavian vein (not shown), and advanced through the patient's venoussystem into the vena cava 90, the right atrium 92 of the heart, andfinally into the coronary sinus 94 to reach the target coronary vein 96.The apparatus 8 may be advanced over a guidewire (not shown), e.g., byplacing the guidewire along the desired path to the coronary vein 96using conventional methods. Exemplary apparatus and methods foraccessing the coronary sinus 94 to deliver the apparatus 8 are disclosedin co-pending application Ser. No. 10/447,526, filed May 29, 2003, theentire disclosure of which is expressly incorporated herein byreference.

Because of the relatively low profile of the expandable distal portion18 with the sheath 30 collapsed (which is substantially the size of thestiffening member 20), the apparatus 8 may be able to access smallercoronary veins or be advanced further into a target coronary vein thanthe tubular proximal portion 10 or conventional access sheaths.

Thus, the distal portion 18 with the sheath 30 collapsed may be advancedfirst from the percutaneous site into the right atrium 92 and coronarysinus 94. As the apparatus 8 is advanced further, the distal tip 28 ofthe distal portion 18 may be introduced into the target vein 96. As thisoccurs, the proximal portion 10 may pass through the vena cava 90 andinto the right atrium 92, or even the coronary sinus 94, as shown.Because the proximal portion 10 may only pass through larger, lesstortuous vessels, the larger profile may not impair advancement of theapparatus 8 to place the distal tip within the target vein 96.

If the distal portion 10 has a tapered distal end 14, the distal end 14may also provide a transition to facilitate the tubular portion 10following the smaller distal portion 18. In addition or alternatively,as shown in FIG. 20, an obturator 40 may be provided within theapparatus 8 to facilitate advancing the proximal portion 10 after thedistal portion 18. Once the proximal portion 10 is adequatelypositioned, e.g., within the right atrium 92 or coronary sinus 94, theobturator 40 may be removed.

Once the apparatus 8 is positioned with the expandable distal portion 18in or near the target vein 96, fluoroscopy and/or other external imagingmay be used to facilitate positioning the apparatus 8. Optionally, theapparatus 8 may include one or more radiopaque markers, e.g., on thedistal end 24 of the stiffening member 20, the distal end 34 of thesheath 30, and/or the distal end 14 of the proximal tubular portion 10,to facilitate such imaging. In addition or alternatively, contrast maybe introduced into the vein, e.g., via a fluid lumen in the stiffeningmember 20 of the apparatus 8 and/or through the lumen 34 of the sheath30, to facilitate fluoroscopic imaging. Such imaging may be used toidentify the location of the sheath 30 relative to nearby structures,e.g., to ensure that the apparatus 8 is advanced as close as possible toa target location. In the exemplary embodiment shown in FIG. 7, theapparatus 8 is advanced such that the distal end 34 of the sheath 30 isdisposed within a coronary vein 96 adjacent the left ventricle of thepatient's heart.

The expandable sheath 30 may then be expanded between the distal end 14of the proximal tubular portion 10 and the target vein 96. A fluid,e.g., including saline and/or contrast, may be introduced into thesheath 30 to expand the sheath 30 towards its enlarged condition.Contrast delivered into the sheath 30 may also facilitate imaging thevein 96. In addition or alternatively, an instrument (not shown) may beadvanced through the apparatus 8 to expand the sheath 30.

An electrical pacing lead (not shown) and/or other instrument may thenbe advanced through the proximal tubular portion 10 and the sheath 30(which may expand or further expand the sheath 30) until the lead isdisposed within the vein 96 beyond the distal tip 28. Because cardiacleads are extremely flexible or floppy, the relative strength and/orrigidity of the proximal portion 10 may facilitate advancing the leadthrough larger vessels, where the lead may otherwise wander or bind up.As the lead enters the sheath 30, the sheath 30 may provide a lubriciousinterface between the lead and the surrounding vessel wall, which mayfacilitate advancing the lead deeper into the patient's vasculature.

Once the lead is delivered, the apparatus 8 may be removed. For example,as described above, a handle, such as handle 50 described above (notshown in FIG. 7, see FIGS. 9-10C), may be provided that includes aninner member 60 and an outer member 70 to which the tubular proximalportion 10 is attached. In this embodiment, the cardiac lead may beadvanced into the inner member 60 through the valve 52, and,consequently into the proximal portion 10 and sheath 30.

To remove the apparatus 8, the outer member 70 may be retractedproximally, thereby withdrawing the tubular proximal portion 10, as wellas the distal portion 18 (i.e., the stiffening member 20 and sheath 30),proximally from the patient's body. As the sheath 30 is removed from thepercutaneous site, the sheath 30 may be split, e.g., by a blade 78 orother slitter tool (not shown) on the inner member 60.

While the outer member 70, tubular proximal portion 10 and expandabledistal portion 18 are removed, the inner member 60 may be maintainedsubstantially stationary, thereby maintaining the end of the lead withinthe target vein 96. Once the tubular proximal portion 10 and sheath 30are removed from the patient, the inner member 60 may also be removed,while maintaining the lead substantially stationary. Because the innermember 60 has a relatively short length, the inner member 60 may beremoved more easily with reduced risk of displacement of the lead,thereby ensuring that the lead remains within the target vein 96.

Turning to FIGS. 8A-8J, another method is shown for delivering anelectrical pacing lead 100 into a coronary vein 96, e.g., through theright atrium (not shown) and coronary sinus 94 of the heart, similar tothe previous embodiment. This method may be particularly useful fordelivering a lead into a target vein 96 that is difficult to access,e.g., if it branches acutely from an adjacent vessel 95. Initially, asshown in FIGS. 8A-8C, an apparatus 8 may be introduced through thecoronary sinus 94 into the vessel 95 adjacent the target vein 96.Generally, the apparatus 8 includes a tubular proximal portion 10, andan expandable distal portion 18, similar to the previous embodiments.The distal portion 18 includes a pushable stiffening member 20 carryinga balloon 27 or other expandable occlusion member and an expandablesheath 30.

As shown in FIGS. 8A and 8B, the apparatus 8 may be advanced into thevessel 95 with the sheath 30 and balloon 27 initially collapsed. Theapparatus 8 may be advanced over a guidewire or other rail (not shown).Optionally, contrast and the like may delivered via a lumen in thestiffening member 20 to facilitate fluoroscopic imaging of the patient'svasculature, e.g., to facilitate advancing the apparatus 8, and/orpositioning the balloon 27 distally to the target vein 96.Alternatively, the balloon 27 may be provided on a separate catheter orother balloon device (not shown), and the apparatus 8 may be advancedover the balloon device.

As shown in FIG. 8C, once the balloon 27 is positioned at a desiredlocation, e.g., immediately distal to the target vein 96, the balloon104 may be expanded to at least partially occlude the vessel 95 and/orto substantially seal the vessel 95 distal to the target vein 96 (e.g.,if additional contrast delivery is desired for fluoroscopic imaging). Inaddition, the balloon 27 may substantially anchor the stiffening member20 relative to the target vein. As shown in FIG. 8C, the tubularproximal portion 10 may be sufficiently long to enter the coronary sinus94 when the balloon 27 is positioned adjacent the target vein 96.

Turning to FIG. 8D, once the balloon 27 is positioned and expanded toocclude the vessel 95 and/or anchor the stiffening member 20, the sheath30 may be expanded, if desired. Alternatively, the sheath 30 may remaincollapsed (but may be released from any constraints) until the lead 100is advanced into the sheath 30. In a further, alternative, the sheath 30may be expanded before the balloon 27 is expanded.

Turning to FIGS. 8E-8H, a lead 100 may then be advanced through theapparatus 8 into the target vein 96. For example, the lead 100 may beinserted through a valve 52 of a handle 50 on a proximal end 12 (all notshown, see, e.g., FIG. 1A) of the apparatus 8 into the tubular proximalportion 10 and advanced until the lead 100 enters the expandable distalportion 18, as shown in FIG. 8E. As the lead 100 is advanced further,the sheath 30 may expand or otherwise accommodate guiding the lead 100through the coronary veins into vessel 95, as shown in FIGS. 8E and 8F.

Turning to FIG. 8G, the lead 100 may eventually exit from the distal end34 of the sheath 30 and become exposed within the vessel 95. As the lead100 is advanced further, the lead 100 may contact the balloon 27.Because the balloon 27 substantially occludes the vessel 95 distal tothe target vein 96, as the lead 100 is advanced further, the onlyavailable path is into the target vein 96. Thus, the balloon 27 mayassist in redirecting the lead 100 into a target vein 96 that mayotherwise be difficult to access, as shown in FIG. 8H.

Turning to FIG. 8I, once the lead 100 is positioned in the target vein96, the balloon 27 may be deflated or otherwise collapsed, and theapparatus 8 may be withdrawn from the vessel 95, the coronary sinus 94,and ultimately out of the patient's body. As shown in FIG. 8J, the lead100 may remain implanted within the target vein 96 (or further downanother branch, if desired). Implantation of the lead 70 may then becompleted, e.g., including connecting the proximal end to a pacemakerand the like (not shown), using conventional methods.

Turning to FIGS. 19A-19C, in an alternative embodiment, an expandablesheath apparatus 208 may be provided that includes a stiffening member220 and an expandable sheath 230, similar to the other embodimentsdescribed herein. Optionally, the apparatus 208 may include one or moreof a tubular proximal portion, a handle, and the like (all not shown),also similar to the embodiments described above.

Unlike the previous embodiments, the apparatus 208 includes a balloon orother expandable member 260 on a distal end 234 of the sheath 230. Thestiffening member 220 or sheath 230 may include a lumen (not shown) thatcommunicates with an interior of the balloon 260, for deliveringinflation media into the balloon 260 from a proximal end (not shown) ofthe apparatus 208. Thus, the balloon 260 may be expanded or collapsed bydelivering or evacuating fluid into and out of the balloon 260.

As best seen in FIG. 19B, the balloon 260 includes a passage 262therethrough that communicates with a lumen 236 of the sheath 230. Asshown, the passage 260 includes a bend that terminates in a transverseopening 264 in an outer wall of the balloon 260. As shown, the passage260 extends substantially perpendicular to the stiffening member 220,although it will be appreciated that the passage 260 and opening 264 mayprovide any desired lateral or other transverse orientation.

The apparatus 208 may be used for delivering a lead 100, similar to theprevious embodiments. For example, as shown in FIG. 19A, with the sheath230 and balloon 260 collapsed, the apparatus 8 may be advanced into avessel 95 until the balloon 260 is disposed adjacent to a target vessel96. Once properly positioned, the balloon 260 may be expanded, e.g., toopen the passage 262 and/or to anchor the apparatus 208 relative to thevessel 95. As best seen in FIG. 19B, the balloon 208 is preferablyexpanded with the opening 264 disposed in alignment with the targetvessel 96.

Thereafter, as shown in FIG. 19C, a lead 100 may be advanced through theapparatus 208, i.e., through the lumen 236 of the sheath 230 until thelead 236 enters the passage 262. Because of the floppy structure of thelead 100 and/or the radius of the passage 262, the lead 100 may beadvanced through the passage 262, out the opening 264, and into thetarget vessel 96. The lead 100 may then be implanted within the targetvessel 96 or otherwise further manipulated, as desired. Once the lead100 is positioned at a desired implantation site, the balloon 260 may becollapsed, and the apparatus 208 may be removed from the vessel 95 andout of the patient's body.

Turning to FIGS. 17 and 18A-18C, a thin sleeve 106 is shown that may bedelivered in conjunction with a lead 100, e.g., a cardiac pacing lead.As best seen in FIG. 17, the sleeve 106 may include a tubular section107 and a stent-like structure 108 on one or both ends of the tubularsection 107. It will be appreciated that any self-expanding orballoon-expandable stent structures may be provided on the ends of thetubular section 107.

Turning to FIG. 18A, in one embodiment, the thin sleeve 106 may beprovided on an exterior of a lead 100, e.g., at an intermediate locationon the lead 100. Otherwise, the lead 100 may be of conventional, knownconstruction. The lead 100, carrying the sleeve 106, may be deliveredinto a patient's body, e.g., through the right atrium 92, the coronarysinus 94, and into the coronary veins (not shown). Preferably, thesleeve 106 is provided at a predetermined intermediate location on thelead 110, such that, when a tip of the lead is delivered into a targetvein, the sleeve 106 is disposed within the coronary sinus 96, as shownin FIG. 18A. The lead 100 may be delivered using the apparatus andmethods described herein, or using conventional methods.

Generally, after a lead, such as lead 100, is implanted, the wall of thecoronary sinus may fibrose or otherwise attach to the lead 100. Becausethe sleeve 106 is disposed around the lead 100, any tissue fibrosis mayattach to the sleeve 106, rather than to the lead 100 itself.Thereafter, if it is desired to remove or move the lead 100 (e.g., asoften becomes necessary over time as the heart remodels itself to CRTtherapy), the lead 100 may be manipulated or even removed, while thesleeve 106 remains in place. Without the sleeve 106, if the lead 100 isremoved or otherwise moved, there is a substantial risk that the wall ofthe coronary sinus may rupture or otherwise be damaged due to the tissuefibrosis, requiring acute treatment of the patient.

Optionally, as shown in FIG. 18B, a balloon device may be used to expandthe thin sleeve 106, e.g., to plastically expand the stents 108 intoengagement with the surrounding tissue of the coronary sinus 96.Alternatively, an overlying sleeve or other constraint may be used tohold the thin sleeve 106, such that, when the constraint is removed, thethin sleeve 106 may resiliently expand to engage the tissue of thecoronary sinus 96.

Such a balloon or constraint may be provided on the lead 100 or on anapparatus (not shown) used to deliver the lead 100, e.g., on an exteriorof a proximal portion of any of the apparatus described herein.Alternatively, the thin sleeve 106 may be delivered independently, e.g.,before the lead 100 is delivered through the coronary sinus 96.

In other alternatives, the lead may include a drug or other materialembedded within or otherwise carried by the lead that may prevent orminimize tissue fibrosis to the lead. In addition or alternatively, theouter surface of the lead may be treated, e.g., by micro-texturing thatmay prevent surrounding tissue from binding to the lead.

Turning to FIGS. 24A and 24B, another embodiment of an expandable sheathapparatus 109 is shown that includes an elongate stiffening member 120having a proximal end 122 and a distal end 124. The apparatus 109further includes a flexible sheath 130 affixed or otherwise secured tothe elongate stiffening member 130 along its length. The flexible sheath130 is shown in a collapsed state in FIG. 24A, and is shown in anexpanded or partially expanded state in FIG. 24B.

The flexible sheath 130 may be affixed or otherwise secured to theelongate stiffening member 120 using any number of configurations. FIGS.25-31 are cross-sectional views of alternative embodiments of theapparatus 109, taken along the line A-A shown in FIG. 24A.

FIG. 25 illustrates a cross-sectional view of the distal portion of theapparatus 109 illustrating one embodiment of securing the elongatestiffening member 120 to the sheath 130. In this embodiment, theelongate stiffening member 120 is external to the lumen of the sheath130. The elongate stiffening member 120 is slit along its length to forma slot 120(a). A portion of the flexible sheath 30 is then inserted intothe slot 120(a) and into the interior lumen 120(b) of the elongatestiffening member 120. The portion of the flexible sheath 130 inside theelongate stiffening member 120 may then be affixed or otherwise bondedto the internal surface 120(c) of the elongate stiffening member 120.

In an alternative embodiment, a secondary tube 121 may be insertedthrough the lumen 120(b) of the elongate stiffening member 120 such thatthe sheath 130 is sandwiched between the exterior of the secondary tube121 and the internal surface 120(c) of the elongate stiffening member120. A mechanical junction is formed between elongate stiffening member120 and the flexible sheath 130. This structure is particularlyadvantageous for materials that are difficult to heat or chemicallybond, such as fluoropolymers. For example, the elongate stiffeningmember 120 and secondary tube 121 may be constructed out of a polymermaterial that reflows with heat (e.g., ePTFE) or a material coated withflowable polymer material. A mechanical lock may be achieved between theelongate stiffening member 120 and secondary tube 121 upon the reflowingof polymer material through the pores of the ePTFE within the sheath130.

FIG. 26 is a cross-sectional view of the distal portion of the apparatus109, illustrating another construction for securing the elongatestiffening member 120 to the sheath 130. In this embodiment, the sheath130 is formed into first and second separate lumens 130′ and 130.″ Thefirst lumen 130′ is the primary lumen through which an instrument, suchas an electrical pacing lead, passes. The elongate stiffening member 120is received in the second lumen 130.″ The elongate stiffening member 120may be bonded along its entire length or at intervals to an interiorsurface 130(a) of the second lumen 130.″Alternatively, as is shown inFIG. 26, the elongate stiffening member 120 may be slidable within thesecond lumen 130.″ In the embodiment shown in FIG. 26, the sheath 130having first and second lumens 130,′ 130″ is preferably formed byco-extruding a polymer material of the type described above.

FIG. 27 illustrates a cross-sectional view of the distal portion of theapparatus 109, illustrating still another construction for securing theelongate stiffening member 120 to the sheath 130. Similar to theembodiment discussed above and shown in FIG. 27, the sheath 130 isformed into first and second separate lumens 130′ and 130.″ The firstlumen 130′ is the primary lumen through which an instrument, such as anelectrical pacing lead, passes. The second lumen 130″ contains theelongate stiffening member 120. The elongate stiffening member 120 maybe bonded along its entire length or at intervals to an interior surface130(a) of the second lumen 130.″ Alternatively, as is shown in FIG. 27,the elongate stiffening member 120 may be slidable within the secondlumen 130.″ The first and second lumens 130′, 130″ of the sheath 130 arejoined by a spine 130(b), which preferably runs along the entire lengthof the sheath 130. The first and second lumens 130′, 130″ are preferablyformed by co-extruding a polymer material of the type described above.In an alternative configuration, the spine 130(b) may be formed from abonding material that links or otherwise connects the first and secondlumens 130′, 130″ of the flexible sheath 130.

FIG. 28 shows a cross-sectional view of the distal portion of theapparatus 109, illustrating still another construction for securing theelongate stiffening member 120 to the sheath 130. In this embodiment,the second lumen 130″ is located within the primary lumen 130′ of theflexible sheath 130. The elongate stiffening member 120 is disposedwithin the second lumen 130″ and may be bonded to an interior surface,or, alternatively, may be slidable therein. The advantage to theembodiment shown in FIG. 28 is that the profile of the apparatus 109 maybe reduced, thereby making it easier to advance the apparatus 109 withinparticularly narrow passageways or vessels.

FIG. 29 illustrates yet another configuration of the distal end of theapparatus 109. In this embodiment, the structure shown in FIG. 27 may beinverted, thereby placing the second lumen 130″ within the interior ofthe primary lumen 130′ of the sheath 130. The inverting process may beaccomplished by pulling an end of the sheath 130 shown in FIG. 27through the primary lumen 130.′ This embodiment is particularlyadvantageous for two reasons. First, the cross-sectional profile may bereduced by placing the second lumen 130″ within the interior of theprimary lumen 130.′ Second, the spine 130(b) may serve as a barrier thatprevents an instrument, such as an electrical pacing lead, from coilingor wrapping around the second lumen 130.″

FIGS. 30A and 30B illustrate yet another configuration of the distal endof the apparatus 109. In this embodiment, the flexible sheath 130 formsfirst, second and third lumens 130,′ 130,″ 130.′″ The first or primarylumen 130′ may be used to receive an instrument, such as an electricalpacing lead, and the like. The second lumen 130″ may receive theelongate stiffening member 120 (not shown). The third lumen 130′″ may beused, for example, to receive an instrument, such as a guidewire and thelike. Alternatively, the third lumen 130′″ may be used to receive orcontain a contrast solution (not shown) for imaging the location of theapparatus 109 within a patient. The third lumen 130′″ may enclose thesecond lumen 130,″ as is shown in FIG. 30A, or may be opposite thesecond lumen 130,″ shown in FIG. 30B.

FIGS. 31A, 31B, and 31C illustrate a method for constructing a flexiblesheath 130 having first, second, and third lumens 130,′ 130,″ and 130′″out of a cast film. With reference to FIG. 31A, a film 140 may beprovided having a base layer 140(a) of PTFE and a surface layer of FEP140(b). If a third lumen 130′″ is desired, a separate layer of film 142having a base layer 142(a) of PTFE and a surface layer of FEP 142(b) maybe provided adjacent to film 140. The smaller layer of film 142 isoriented to place the two FEP surface layers 140(b), 142(b) in contactwith one another. A space 143 or lumen may also be formed between thetwo layers of film 140, 142. The two layers of film 140, 142 may then bebonded to one another at the interfaces by, for example, heat bondingthe two opposing FEP-FEP surfaces 140(b), 142(b).

After bonding the two opposing FEP-FEP surfaces 140(b), 142(b), thestructure shown in FIG. 31B may be formed by folding the sheet 140 ontoitself and heat bonding opposing FEP-FEP surfaces 140(b) at locations Aand B as shown in FIG. 31B. In this regard, a sheath 130 may be formedhaving first, second, and third lumens 130,′ 130,″ and 130.′″ The firstlumen 130′ is preferably used to receive an instrument, such as anelectrical pacing lead (not shown). The second lumen 130″ is preferablyused to house the elongate stiffening member 120. The third lumen 130′″is preferably used to receive or contain contrast solution for imagingthe location of the apparatus 109.

FIG. 31C illustrates a sheath 130 created by inverting the structureshown in FIG. 31B. The sheath 130 may be created by pulling an end ofthe sheath 130 shown in FIG. 31B through the first or primary lumen130.′ This structure is particularly preferred because it places thelubricious PTFE layer 140(a) on the interior of the primary lumen 130.′

FIG. 32 illustrates an auto-sealing nature of a flexible sheath 130,according to another embodiment. When placed inside a pressurizedenvironment within the body (e.g., within a blood vessel), the flexiblesheath 130 may collapse when the pressure differential between theoutside of the sheath 130 and the inside of the sheath 130 is sufficientto overcome the “hoop” strength of the sheath 130.

FIG. 32 illustrates several different pressures experienced by theapparatus 109 100 located within a blood vessel. P₀ represents the bloodpressure of the blood vessel. P₁ represents the pressure at the distalend of the sheath 130 while P₂ represents the pressure at a proximalregion of the sheath 130. P₃ represents atmospheric pressure. Given thatP₁>P₂>P₃ and at the distal tip of the sheath 130 P₀≈P₁, then the sheath130 may collapse when the differential between P₂ and P₀ is sufficientto overcome the resilient or “hoop” strength of the sheath 130.

In thin-walled materials with a low “hoop” strength, the collapse of thesheath 130 occurs readily. The collapse of the sheath 130 (either onitself or around another structure such as an elongate stiffening member120) may prevent blood loss and/or further reinforce the pressuredifferential that keeps the sheath material in the collapsedconfiguration.

While the invention is susceptible to various modifications, andalternative forms, specific examples thereof have been shown in thedrawings and are herein described in detail. It should be understood,however, that the invention is not to be limited to the particular formsor methods disclosed, but to the contrary, the invention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the appended claims.

1. An apparatus for providing access to a body lumen, comprising: atubular member comprising a proximal end, a distal end sized forinsertion into a body lumen, and a lumen extending between the proximaland distal ends; an elongate member extending from the distal end of thetubular member, the elongate stiffening member terminating in a distaltip; and an expandable sheath extending along at least a portion of theelongate member, the sheath having first and second lumens, the firstsheath lumen communicating with the tubular member lumen, and elongatemember being disposed at least partially within the second sheath lumen.2. The apparatus of claim 1, wherein the second sheath lumen is disposedexternal to the first sheath lumen.
 3. The apparatus of claim 1, whereinthe second sheath lumen is disposed internal to the first sheath lumen.4. The apparatus of claim 3, wherein the elongate member is slidablewith respect to the second sheath lumen.
 5. The apparatus of claim 3,wherein the elongate member is at least partially secured to a surfaceof the second sheath lumen.
 6. The apparatus of claim 3, wherein thesecond sheath lumen is disposed along a spine between the first andsecond sheath lumens.
 7. The apparatus of claim 1, further comprising athird sheath lumen for receive a contrast solution.
 8. An apparatus forproviding access to a body lumen, comprising: an expandable tubularmember comprising a proximal end, a distal end sized for insertion intoa body lumen, and a wall defining an outer lumen extending between theproximal and distal ends, and an inner lumen extending between theproximal and distal ends, the inner lumen at least partially floatingwithin the outer lumen; and an elongate stiffening member disposedwithin the inner lumen and extending between the proximal and distalends of the expandable tubular member, the stiffening member terminatingin a distal tip.
 9. The apparatus of claim 8, wherein the inner lumencomprises a portion of the wall of the expandable tubular member thatextends into outer lumen.
 10. The apparatus of claim 9, wherein the wallcomprises a sheet having first and second ends rolled into a tubularshape, the sheet being attached to itself adjacent the first and secondends to define the outer lumen, such that the first and second endsextend into the outer lumen to define the inner lumen.
 11. The apparatusof claim 10, wherein the first and second ends are attached to oneanother to define the inner lumen.
 12. The apparatus of claim 8, whereinthe stiffening member is attached to at least a portion of a wall of theinner lumen.
 13. The apparatus of claim 8, wherein an inner surface ofthe outer lumen comprises a lubricious material.
 14. The apparatus ofclaim 8, wherein the sheath comprises a wall thickness not more thanabout 0.01 inch (0.25 mm).
 15. The apparatus of claim 8, wherein thesheath comprises one or more additional lumens that extendlongitudinally along the wall of the sheath.
 16. The apparatus of claim8, wherein the wall of the tubular member comprises a lubricous innerlayer within the outer lumen and a heat-sealable outer layer.
 17. Theapparatus of claim 16, wherein the inner layer comprises one of PTFE andePTFE, and the outer layer comprises FEP.
 18. A method for making anexpandable sheath using a film including first and second ends, firstand second side edges, a first lubricious layer and a second layer, themethod comprising: rolling the film such that the first and second sideedges are adjacent one another to define a lumen such that the secondlayer is inside the lumen and the first layer is outside the lumen;bonding the second layer to itself at or near the first and second sideedges; and inverting the film such that the second layer is outside thelumen and the first layer is inside the lumen, thereby providing atubular member having a lubricious material within the lumen.
 19. Themethod of claim 18, wherein, after the film is rolled, the second layeris bonded to itself along a plurality of seams extending between thefirst and second ends of the film to define first and second lumensadjacent one another.
 20. The method of claim 19, wherein the film isinverted through the first lumen such that the second lumen is locatedwithin the first lumen.
 21. The method of claim 20, wherein the secondlumen extends from a wall of the outer lumen, thereby coupling thesecond lumen at least partially to the first lumen, while allowing thesecond lumen to float within the first lumen.
 22. The method of claim18, further comprising inserting an elongate stiffening member withinthe second lumen such that the elongate member at least partially floatswithin the first lumen.
 23. The method of claim 22, further comprisingattaching the elongate member to at least a portion of the second lumenwall.
 24. The method of claim 18, wherein the first-layer comprises atleast one of PTFE and ePTFE, and the second layer comprises FEP.
 25. Themethod of claim 18, wherein the second layer is bonded to itself withoutdamaging the first layer.
 26. A method for making an expandable sheath,comprising: providing a film having a first end and a second end, thefilm having a base layer formed from PTFE and a surface layer of FEP;bending the film to bring the surface layer of FEP at or near the firstend adjacent to the surface layer of FEP at or near the second end; andbonding the surface layer of FEP at or near the first end adjacent tothe surface layer of FEP at or near the second end, wherein said bondingstep forms a lumen within the expandable sheath.
 27. The method of claim26, further comprising inverting the lumen within the expandable sheathso as to expose the base layer from PTFE to the internal surface of thelumen.
 28. The method of claim 26, wherein the bonding step forms aplurality of lumens within the expandable sheath.
 29. The method ofclaim 26, wherein bonding step comprises heat bonding.